Quick correction based on the chapter's context/going back through old chapters:
His job seem to be executing those who recovered from falling or resisted it.
And he's not the corrupted priest, that was him calling out the first girl - the priestess who fell to corruption and eventually making contract with a cursed dragon (the black 'veil' covering her), first appearance is ch 14 while the dragon debut at 28.
the 2nd target was a princess who got turned into monster and tried to find a place to belong after finally (re)gaining control of her monster body (first appear ch 9)
the 3rd was an old swordsmaster who got genderbent + unaged to become a young girl, broken out of brainwashing by breaking one of the horn (first appearance ch 8)
His complaint to demon lord seem to essentially be that the departments who made these projects made them way too strong.